CJC-1295 Mechanism of Action — Research Reference

CJC-1295 is a 30-amino-acid analogue of growth hormone-releasing hormone (GHRH 1-29). Two forms appear in the published record — with DAC (Drug Affinity Complex; ~6–8 day half-life) and without DAC ("modified GRF 1-29"; ~30 minute half-life). Both are GHRH receptor agonists; only the pharmacokinetic profile differs.

Receptor Target

CJC-1295 binds the growth hormone-releasing hormone receptor (GHRH-R / GHRHR) on anterior pituitary somatotropes. The receptor is a class-B GPCR distinct from the GHS-R1a ghrelin receptor targeted by GHRPs.

Signal Transduction

GHRH-R activation drives:

1. Gαs → adenylyl cyclase → cAMP → PKA — the canonical GHRH pathway, triggering GH-vesicle exocytosis.
2. CREB phosphorylation → GH gene transcription — sustains somatotrope GH stores during chronic stimulation.
3. MAPK/ERK pathway — supports somatotrope proliferation and granule biogenesis in long-duration studies.

DAC Chemistry

The Drug Affinity Complex is a lysine-maleimide linker on the C-terminus. After injection it forms a covalent thioether bond with the free cysteine-34 residue of endogenous serum albumin. The albumin-conjugated peptide is shielded from DPP-IV and renal clearance, producing a multi-day depot. The non-DAC version (modified GRF 1-29) shares the same four amino-acid substitutions (D-Ala²/Gln⁸/Ala¹⁵/Leu²⁷) that confer DPP-IV resistance but lacks the albumin linker.

Effect on GH-Pulse Architecture

Continuous GHRH stimulation (DAC form) raises tonic GH but flattens pulse amplitude in published primate work. Short-half-life modified GRF 1-29 preserves natural pulse architecture and synergizes cleanly with co-administered GHRPs that act on the parallel ghrelin pathway.

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References

1. Teichman SL, Neale A, Lawrence B, et al. Prolonged stimulation of GH and IGF-I secretion by CJC-1295. J Clin Endocrinol Metab. 2006;91(3):799–805.
2. Ionescu M, Frohman LA. Pulsatile secretion of growth hormone persists during continuous stimulation by CJC-1295. J Clin Endocrinol Metab. 2006;91(12):4792–4797.
3. Mayo KE, Miller T, DeAlmeida V, et al. The growth-hormone-releasing hormone receptor: signal transduction, gene expression, and physiological function. Recent Prog Horm Res. 1995;50:35–73.